Electroplating



Patented Ma 5, i925.

v UNITED STAT Es PATENT FW -If 2 run, 01' KOKOIQ, INDIANA,

A CORPORATION INDIANA.

.nr.ncraornnrme.

Ho Drawing.

To all concern:

Be it known that'I, CHAD H, Hmrrrmms,

' a citizen of the United States, residing at added to cyanide electroplatin Kokomo, in the county of Howard and State of Indiana, have invented certain new and useful Improvements in Electroplating, of which the following is a specification.

This invention relates to electroplating and more particularly to the use of certain addition or-rbrlghtening agents in the cyanide baths of various metals such; as cadmium, copper, silver, zinc and brass used for 'electroplatmg with these metals.-

I have found that protein substances when baths of metals give bright, dense, smoot adherent and continuous deposits. In my application Serial No. 540,566, filed March 2, 1922, I

proteins, and casein is a conjugated proteinibelonging to the phospho-protein family. 'Both belong to the sulpho-phospho grcu of proteins. They are readily soluble in a aline cyanide solutions, particularly when. such solutions contain some free so-. dium hydroxide and function as brightening agents in a ver satisfactory manner giving deposits sharpiy; diii'erent from those obtainable from t e'simple cyanide solutions not only in continuity andhardness, but also in appearance. Under'certain conditions it has been osslble to obta n cadmium depositsso ard that when a piece of steelcarrying the coatilg was flexed spangles of thecoating flew o According to the theory of action of ad:

dition agents given in] Applied Colloid- Chemistry by Bancroft, 1921, pages 165 and 231, some of the addition agent must be adsorbed by the precipitatin metal.- of course indicatesa loss o the addition agent from the plating bath which must be -made up by further additions thereto. If

This

Application med June's, 1924. Serial No. 718,079.

such adsorption does take place, it is very small or almost negligible, as I have found that extremely small quantities of the pro tein addition agents serve for a long period of time. Instances, are known in which commercial plating baths have been used for over a year without any replenishing the addition As stated, the quantity of the addition agent'required is very small. As little as gram of wool 01 gram of casein per gallon of electrolyte has been found to give satisfactory results. The quantity of addition agent preferably used ordinarily is greater than the minimum stated, however, and may vary under dilferent circumstances cm is. nmnnnrns, orxoxoxo, manure, nssrenon are norma rnoonss oorfrom say to ldgrams of wool, or to 2 grams of casein.

The following examples illustrate the invention;

(1) To each gallon of a sodium cadmium cyanide solution containing from A to 6 ounces of metallic cadmium and 2 to 6 ounces of free sodium cyanide per gallon there is added preferably about 1 grams of wool dissolved in a warm concentrated solution of caustic. soda.

' (2) Toeach gallon of a bath containing 1/; to 6 ounces of metallic cadmium and 2 to 6 ounces of sodium cyanide per gallon there is added preferably about 1 grams of casein dissolved in a warm dilute aqueous solution of ammonia. c

Examples might be multiplied in great numberusing different metals, difierent bath compositions and different addition agents, but the foregoing suficiently illustrate the invention.

' This application is a continuation in art of my appl cation Serial No. 540,566, ed

March 2, 1922, referred to above.

I claim:

1. Method ofobtaining bright, dense, coherent deposits of a metal upon another metal which comprises electrodepositing said first named metal from a cyanide solution thereof in the presence of a protein addition agent.

2. Method of obtaining bright, dense, 'coherent deposits of cadmium upon another metal which' comprises electrodepositing cadmium from a cyanide solution thereof in the presence of a rotein addition agent;-

3'. Method of o taining bright, dense, co-

herent deposits of a'metal upon another metal which comprises eleetrodepositin said first named metal from a cyanide so ution thereof to which has been added an alkaline solution of a protein as a brightening a%1ent. 4. Method as defined in claim 3 in w ich the brightening agent is an ammoniacal soaesaese the, brightening: lution of casein.

6. Method as defined in claim 3 in which the brightening agent is a protein of the sulpho-phospho group.

In testimony whereof, I afiix my signaagent is an ammonical soture. I L 

